BEIJING—A pivotal online microfilm, “Old Boys,” which was watched by tens of millions and helped to establish the genre in China, is being made into a feature-length movie.

The filmmakers presented a trailer for the film at a news conference Thursday in Beijing and said it would be shown in Chinese cinemas in May.

The project’s genesis as a 43-minute microfilm that netted nearly 70 million views on a video website demonstrates how online films are influencing the traditional film industry.

The original, funny but poignant film is about a wedding host and a barber who reminiscence about their childhood dreams of making it big in music. They decide to team up for a talent show, but their hopes are dashed when they’re rejected.